Diagnostic Fault Information
Important: Always perform the
Diagnostic System Check - Vehicle
prior to using this diagnostic procedure.
Circuit/System Description
The body control module (BCM) supplies voltage to the audio steering wheel control multiple momentary contact switches and monitors the return signal. Each switch is associated to a set resistance value, when pressed a specific voltage drop occurs through
a series of resistors unique to that switch. The BCM identifies the selection, then sends a serial data message that is received by the component controlled, activating the feature.
Diagnostic Aids
| • | This diagnostic is for the audio steering wheel controls. |
| • | Before diagnosis of the steering wheel controls, ensure the primary controls of the associated component are functioning properly. |
| • | Review schematic when testing switch resistance values. |
| • | If a single switch function is inoperative, test the suspect switch. Refer to component testing. |
Reference Information
Schematic Reference
Steering Wheel Schematics
Connector End View Reference
Description and Operation
Steering Wheel Controls Description and Operation
Electrical Information Reference
Scan Tool Reference
Circuit/System Verification
Ignition ON, observe the BCM data display with the scan tool under Inputs-SWC Bank 1 status. Data displays SW1-SW7 identifying the switch pressed, and Idle when released.
Circuit/System Testing
Caution: Refer to SIR Caution in the Preface section.
- Ignition OFF, disconnect the harness connector at the audio steering wheel control switch.
- Ignition ON, test for ignition voltage between the ignition circuit terminal 3 and ground.
| ⇒ | If less than the specified value, test the ignition circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM. |
- Test for 0 volts between the signal circuit terminal 4 and ground.
| ⇒ | If greater than the specified value, test the signal circuit for a short to voltage. If the circuit tests normal, replace BCM. |
- Test for ignition voltage between the ignition circuit and the signal circuit .
| ⇒ | If less than the specified value, test the signal circuit for an open/high resistance. If the circuit tests normal, replace the BCM. |
- Ignition OFF, disconnect the harness connector C1 at the BCM.
- Test for infinite resistance between the signal circuit terminal 6 and ground.
| ⇒ | If not the specified value, test the signal circuit for a short to ground. If the circuit tests normal, replace the BCM. |
- If all circuits test normal, test or replace switch.
Component Testing
Caution: Refer to SIR Caution in the Preface section.
- Ignition OFF, disconnect the harness connector at the applicable steering wheel control switch.
- Test for infinite resistance between the signal terminal 4 and the ignition terminal 3 with the switch in the open position.
| ⇒ | If not the specified value, replace the switch. |
- Test resistance values between the signal terminal and the ignition terminal with the switch closed in each position. Verify readings are approximate to what the schematic reads.
| ⇒ | If not the specified value, replace the switch. |
Repair Instructions
Important: Always perform the
Diagnostic Repair Verification
after completing the diagnostic procedure.
